Characterizing the Use of Healthcare Access Supports Among People Who Use Drugs in Vancouver, Canada, 2017 to 2020: A Cohort Study.

BACKGROUND: For structurally marginalized populations, including people who use drugs (PWUD), equitable access to healthcare can be achieved through healthcare access supports. However, few studies characterized utilization of formal (eg, outreach workers, healthcare professionals) and informal (eg, friends/family) supports. Therefore, we sought to estimate the prevalence of and factors associated with receiving each type of support among PWUD. METHODS: We used data from 2 prospective cohort studies of PWUD in Vancouver, Canada, in 2017 to 2020. We constructed separate multivariable generalized linear mixed-effects models to identify factors associated with receiving each of the 3 types of supports (ie, healthcare professionals, outreach workers/peer navigators, and informal supports) compared to no supports. RESULTS: Of 996 participants, 350 (35.1%) reported receiving supports in the past 6 months at baseline, through informal supports (6.2%), outreach workers (14.1%), and healthcare professionals (20.9%). In multivariable analyses, HIV positivity, chronic pain, and avoiding healthcare due to the past mistreatment were positively associated with receiving supports from each of healthcare professionals and outreach workers. Men were less likely to receive any types of the supports (all P < .05). CONCLUSIONS: Utilization of healthcare access supports was relatively low in this sample. However, formal supports appeared to have reached PWUD exhibiting more comorbidities and experiencing discrimination in healthcare. Further efforts to make formal supports more available would benefit PWUD with unmet healthcare needs, particularly men.

Cannabidiol as a Harm Reduction Strategy for People Who Use Drugs: A Rapid Review.

OBJECTIVE: The drug poisoning crisis throughout North America necessitates novel harm reduction approaches. Emerging evidence suggests that cannabidiol (CBD) may have some utility as a harm reduction modality for those with problematic substance use. This rapid review aimed to synthesize available evidence on CBD as a potential harm reduction tool for people who use drugs while providing clinical and research insights. METHOD: A systematic search in EMBASE, MEDLINE, CENTRAL, and CINAHL was completed in July 2022. For inclusion, studies had to meet the following criteria: (1) drawn from an adult population of people who use drugs; (2) investigates CBD as an intervention for problematic substance use or harm reduction-related outcomes; (3) be published after the year 2000 and in English; and (4) be primary research or a review article. A narrative synthesis was used to group outcomes relevant to harm reduction and provide clinical and research insights. RESULTS: We screened 3,134 records, of which 27 studies (5 randomized trials) were included. The evidence remains limited, but available studies support the potential utility of CBD to reduce drug-induced craving and anxiety in opioid use disorder. There were low-quality studies suggesting that CBD may improve mood and general well-being of people who use drugs. Evidence suggests that CBD monotherapy may not be an adequate harm reduction strategy for problematic substance use but rather an adjunct to the standard of care. CONCLUSION: Low-quality evidence suggests that CBD may reduce drug cravings and other addiction-related symptoms and that CBD may have utility as an adjunct harm reduction strategy for people who use drugs. However, there is a significant need for more research that accurately reflects CBD dosing and administration regimens used in a real-world context.

Factors associated with self-reported avoidance of harm reduction services during the COVID-19 pandemic by people who use drugs in five cities in the United States and Canada.

BACKGROUND: This study examines individual-level factors associated with avoiding two important health services for people who use drugs-medications for treatment of opioid use disorder and syringe service programs-during the first year of the COVID-19 pandemic. METHODS: Data come from two subsamples of people who use drugs who were active participants in one of nine cohort studies in Vancouver, British Columbia; Baltimore, Maryland; Los Angeles, California; Chicago, Illinois; and Miami, Florida. Participants were interviewed remotely about COVID-19-associated disruptions to healthcare. We estimated the association of demographic, social, and health factors with each outcome using logistic regression among 702 participants (medication analysis) and 304 participants (syringe service analysis.) Analyses were repeated, stratified by city of residence, to examine geographic variation in risk. RESULTS: There were large differences between cities in the prevalence of avoiding picking up medications for opioid use disorder, with almost no avoidance in Vancouver (3%) and nearly universal avoidance in Los Angeles, Chicago, and Miami (>90%). After accounting for between-city differences, no individual factors were associated with avoiding picking up medications. The only factor significantly associated with avoiding syringe service programs was higher levels of self-reported worry about COVID-19. CONCLUSION: During the first year of the COVID-19 pandemic, geographic differences in service and policy contexts likely influenced avoidance of health and harm reduction services by people who use drugs in the United States and Canada more than individual differences between people.

Frequent Cannabis Use Is Negatively Associated with Frequency of Injection Drug Use Among People Who Inject Drugs in a Canadian Setting.

Objectives: High levels of morbidity and mortality associated with injection drug use continue to represent a significant public health challenge in many settings worldwide. Previous studies have shown an association between cannabis use and decreased risk of some drug-related harms. We sought to evaluate the association between high-intensity cannabis use and the frequency of injection drug use among people who inject drugs (PWID). Methods: The data for this analysis were collected from three prospective cohorts of PWID in Vancouver, Canada, between September 2005 and May 2018. Generalized linear mixed-effects models were used to analyze the association between daily cannabis use and the frequency of injecting illegal drugs (i.e., self-reported average number of injections per month). Results: Among the 2,619 active PWID, the frequency of injection drug use was significantly lower among people who use cannabis daily compared with people who use it less than daily (adjusted odds ratio [AOR]=0.84, 95% confidence interval [CI]: 0.73-0.95). Sub-analyses indicated that this effect was restricted to the frequency of illegal opioid injection (AOR=0.78, 95% CI: 0.68-0.90); the association between daily cannabis use and the frequency of illegal stimulant injection was not significant (AOR=1.08, 95% CI 0.93-1.25). Discussion: The findings from these prospective cohorts suggest that people who use cannabis daily were less likely to report daily injection of illegal drugs compared with people who use it less than daily. These results suggest the potential value of conducting experimental research to test whether controlled administration of cannabinoids impacts the frequency of illegal opioid injection among PWID.

Greater Pain Severity is Associated with Inability to Access Addiction Treatment Among a Cohort of People Who Use Drugs.

AIM: Given that co-occurring pain is prevalent among people who use drugs (PWUD), we sought to explore the effect of pain severity on accessing addiction treatment. METHODS: Data were derived from two prospective cohort studies of PWUD in Vancouver, Canada from June 2014 to May 2016. Multivariable generalized linear mixed-effects multiple regression (GLMM) analyses were used to investigate the association between average pain severity and self-reported inability to access addiction treatment. RESULTS: Among 1348 PWUD, 136 (10.1%) reported being unable to access addiction treatment at least once over the study period. Individuals who reported being unable to access addiction treatment had a significantly higher median average pain severity score (median=5, IQR=0-7) compared to individuals reporting no inability to access addiction treatment (median=3, IQR=0-6, p=0.038). Greater pain severity was independently associated with higher odds of reporting inability to access addiction treatment (AOR: 1.75, 95%CI: 1.08-2.82 for mild-moderate vs no pain; AOR: 1.98, 95%CI: 1.27-3.09 for moderate-severe vs no pain). CONCLUSION: PWUD with greater pain severity may be at higher risk of being unable to access addiction treatment, or vice versa. While further research is needed to confirm causal associations, these data suggest that there may be underlying pathways or mechanisms through which pain may be associated with access to addiction treatment for PWUD.

Trajectories of injection drug use among people who use drugs in Vancouver, Canada, 1996-2017: growth mixture modeling using data from prospective cohort studies.

BACKGROUND AND AIMS: Injection drug use patterns are known to change over time, although such long-term changes have not been well described. We sought to characterize longitudinal trajectories of injection drug use and identify associated factors. DESIGN: Data were derived from the Vancouver Injection Drug Users Study and AIDS Care Cohort to evaluate the Exposure to Survival Services study, two prospective cohorts involving people who inject drugs in Vancouver, Canada between 1996 and 2017. Growth mixture modeling was applied to identify distinct injection drug use trajectories. Multinomial logistic regression was used to identify baseline factors associated with each trajectory. SETTING: Canada. PARTICIPANTS: A total of 2057 participants who reported having used illicit drugs via injection in the past 6 months at the baseline visit were included in the study. The median time since first injection drug use at baseline was 14.8 years (quartile 1-quartile 3: 6.5-24.3). MEASUREMENTS: Information regarding self-reported injection drug use during the past 6 months was collected at baseline and semi-annually thereafter via interviewer-administered questionnaires. FINDINGS: Participants were followed for a median of 113.4 months (quartile 1-quartile 3: 63.4-161.7). Five trajectories were identified: persistent high frequency injection (507, 24.6%); high frequency injection with late decrease (374, 18.2%); gradual cessation (662, 32.2%); early cessation with late relapse (227, 11.0%); and early cessation (287, 14.0%). Factors found to be associated with distinct trajectories included: daily heroin injection, binge injection drug use, age, not being in a stable relationship and year of study enrollment. CONCLUSIONS: People who used drugs in Vancouver, Canada from 1996 to 2017 appeared to follow five drug use trajectories, ranging from persistent high frequency use to early cessation. Almost 25% of participants remained high-frequency injectors over the study period.

Predictors of Antiretroviral Adherence Self-efficacy Among People Living With HIV/AIDS in a Canadian Setting.

BACKGROUND: Suboptimal adherence to antiretroviral therapy (ART) among people living with HIV/AIDS (PLWHA) who use illicit drugs remains an ongoing health concern. Although health outcomes associated with adherence self-efficacy have been well-documented, there is dearth research exploring the predictors of this construct. This study sought to identify possible determinants of adherence self-efficacy among a cohort of PLWHA who use illicit drugs. METHODS: From December 2004 to May 2014, we collected data from the AIDS Care Cohort to evaluate Exposure to Survival Services, a prospective cohort of adult PLWHA who use illicit drugs in Vancouver, Canada. We used multivariate generalized estimating equation analyses to identify longitudinal factors independently associated with higher adherence self-efficacy. RESULTS: Among 742 participants, 493 (66.4%) identified as male and 406 (54.7%) reported white ancestry. In multivariate generalized estimating equation analysis, older age at ART initiation (adjusted odds ratio [AOR] = 1.02, 95% confidence interval [CI]: 1.00 to 1.03) and recent year of baseline interview (AOR = 1.08, 95% CI: 1.05 to 1.11) were independently associated with higher adherence self-efficacy, whereas homelessness (AOR = 0.78, 95% CI: 0.65 to 0.94), ≥daily crack smoking (AOR = 0.81, 95% CI: 0.68 to 0.96), experienced violence (AOR = 0.82, 95% CI: 0.69 to 0.98), and childhood abuse (AOR = 0.75, 95% CI: 0.60 to 0.92) were negatively associated. CONCLUSIONS: These findings highlight the potential role that personal and contextual factors can play in predicting levels of ART adherence self-efficacy. Future research should seek to identify and validate strategies to optimize adherence self-efficacy.

Incarceration history and risk of HIV and hepatitis C virus acquisition among people who inject drugs: a systematic review and meta-analysis.

BACKGROUND: People who inject drugs (PWID) experience a high prevalence of incarceration and might be at high risk of HIV and hepatitis C virus (HCV) infection during or after incarceration. We aimed to assess whether incarceration history elevates HIV or HCV acquisition risk among PWID. METHODS: In this systematic review and meta-analysis, we searched MEDLINE, Embase, and PsycINFO databases for studies in any language published from Jan 1, 2000 until June 13, 2017 assessing HIV or HCV incidence among PWID. We included studies that measured HIV or HCV incidence among community-recruited PWID. We included only studies reporting original results and excluded studies that evaluated incident infections by self-report. We contacted authors of cohort studies that met the inclusion or exclusion criteria, but that did not report on the outcomes of interest, to request data. We extracted and pooled data from the included studies using random-effects meta-analyses to quantify the associations between recent (past 3, 6, or 12 months or since last follow-up) or past incarceration and HIV or HCV acquisition (primary infection or reinfection) risk among PWID. We assessed the risk of bias of included studies using the Newcastle-Ottawa Scale. Between-study heterogeneity was evaluated using the I2 statistic and the P-value for heterogeneity. FINDINGS: We included published results from 20 studies and unpublished results from 21 studies. These studies originated from Australasia, western and eastern Europe, North and Latin America, and east and southeast Asia. Recent incarceration was associated with an 81% (relative risk [RR] 1·81, 95% CI 1·40-2·34) increase in HIV acquisition risk, with moderate heterogeneity between studies (I2=63·5%; p=0·001), and a 62% (RR 1·62, 95% CI 1·28-2·05) increase in HCV acquisition risk, also with moderate heterogeneity between studies (I2=57·3%; p=0·002). Past incarceration was associated with a 25% increase in HIV (RR 1·25, 95% CI 0·94-1·65) and a 21% increase in HCV (1·21, 1·02-1·43) acquisition risk. INTERPRETATION: Incarceration is associated with substantial short-term increases in HIV and HCV acquisition risk among PWID and could be a significant driver of HCV and HIV transmission among PWID. These findings support the need for developing novel interventions to minimise the risk of HCV and HIV acquisition, including addressing structural risks associated with drug laws and excessive incarceration of PWID. FUNDING: Engineering and Physical Sciences Research Council, National Institute for Health Research, National Institutes of Health.

Linking opioid-induced hyperalgesia and withdrawal-associated injury site pain: a case report.

INTRODUCTION AND OBJECTIVES: Understanding the details of one individual's experience with pain, opioid use and withdrawal may generate insights into possible relationships between opioid-induced hyperalgesia and withdrawal-associated injury site pain (WISP). METHODS: This case study was extracted from a mixed methods study that characterized WISP. In 2014, the individual was recruited from a primary care clinic that prescribes opioid agonist therapy. In an interview, she completed a 35-item survey and elaborated on her own experience. Follow-up contact was made in June of 2017. RESULTS: This 34-year-old white woman had several twisting injuries of her right knee between ages 13 and 15. The pain resolved each time in a few days, and she was pain free for 15 years. Around age 30, she initiated illicit oxycodone recreationally (not for pain) and developed an opioid use disorder. On detoxification, she experienced severe knee pain for 6 weeks that resolved postdetoxification but returned after subsequent oxycodone use and withdrawal episodes along with generalized skin sensitivity. This experience of WISP became a barrier to opioid cessation. Although nonsteroidal anti-inflammatories and gabapentin relieved WISP and methadone therapy assisted her opioid use disorder, an eventual change to sublingual buprenorphine/naloxone provided superior control of both. CONCLUSION: This case report illustrates that both opioid use and withdrawal can reactivate injury site pain, which can increase with dose escalation and repeated withdrawal events. The timing, trajectory, and neuropathic features of WISP reported here are consistent with those previously reported for the development of opioid-induced hyperalgesia, possibly linking these phenomena.

Cannabis use is associated with lower rates of initiation of injection drug use among street-involved youth: A longitudinal analysis.

INTRODUCTION AND AIMS: Street-involved youth are known to be at elevated risk of initiating injection drug use. However, the impact of so-called 'gateway' drugs, such as cannabis, on injection initiation is unknown. The objective of this study was to examine the association between cannabis use and initiation of injection drug use among a prospective cohort of street-involved youth in Vancouver, Canada. DESIGN AND METHODS: Data for this study were collected from the At-Risk Youth Study. From September 2005 to May 2015, participants aged 14-26 who reported illicit drug use were recruited into this open prospective cohort study. An extended Cox regression model with time-updated covariates was used to identify factors independently associated with injection initiation. RESULTS: During the study period, 481 street-involved youth were included in this study. Of these, 228 (47.4%) reported at least daily cannabis use, and 103 (21.4%) initiated injection drug use. In a multivariable analysis, ≥daily cannabis use was associated with slower rates of injection initiation (adjusted relative hazard 0.66, 95% confidence interval 0.45-0.98; P = 0.038). Sub-analyses revealed that cannabis use was negatively associated with initiation of injection stimulants but not initiation of injection opioids. DISCUSSION AND CONCLUSIONS: Given the expansion of cannabis legalisation throughout North America, it is encouraging that cannabis use was associated with slower time to initiation of injection drug use in this cohort. This finding challenges the view of cannabis as a gateway substance that precipitates the progression to using harder and more addictive drugs.

Incidence and predictors of mental health disorder diagnoses among people who inject drugs in a Canadian setting.

INTRODUCTION AND AIMS: Limited attention has been given to the predictors of mental health diagnoses among people who inject drugs (PWID) in community settings. Therefore, we sought to longitudinally examine the prevalence, incidence and predictors of mental disorder diagnosis among a community-recruited cohort of PWID. DESIGN AND METHODS: Data were derived from two prospective cohort studies of PWID (VIDUS and ACCESS) in Vancouver, Canada between December 2005 and May 2015. We used multivariable extended Cox regression to identify factors independently associated with self-reported mental disorder diagnosis during follow-up among those without a history of such diagnoses at baseline. RESULTS: Among the 923 participants who did not report a mental disorder at baseline, 206 (22.3%) reported a first diagnosis of a mental disorder during follow-up for an incidence density of 4.29 [95% confidence interval (CI) 3.72-4.91] per 100 person-years. In the multivariable analysis, female sex [adjusted hazards ratio (AHR) = 1.74, 95% CI 1.29-2.33], experiencing non-fatal overdose (AHR = 2.33, 95% CI 1.38-3.94), accessing any drug or alcohol treatment (AHR = 1.68, 95% CI 1.24-2.27), accessing any community health or social services (AHR = 1.53, 95% CI 1.02-2.28) and experiencing violence (AHR = 1.60, 95% CI 1.12-2.29) were independently associated with a mental disorder diagnosis at follow-up. DISCUSSION AND CONCLUSIONS: We observed a high prevalence and incidence of mental disorders among our community-recruited sample of PWID. The validity and implication of these diagnoses for key substance use and public health outcomes are an urgent priority.

Knowledge of hepatitis C and treatment willingness amongst people who inject drugs in an era of direct acting antivirals.

BACKGROUND: Knowledge of hepatitis C virus (HCV) is believed to be important in altering risk behaviour, improving engagement in care, and promoting willingness to initiate HCV treatment. We assessed factors associated with HCV knowledge and treatment willingness amongst people who inject drugs (PWID) in an era of direct acting antivirals. METHODS: Data were derived from three prospective cohort studies of PWID in Vancouver, Canada, between June 2014 and May 2015. HCV knowledge and treatment willingness were assessed using a Likert scale. Multivariable linear regression identified factors associated with higher HCV knowledge and treatment willingness. RESULTS: Amongst 630 participants, mean scores for HCV knowledge and treatment willingness were 25.41 (standard deviation [SD]: 2.52) out of 30, and 6.83 (SD: 1.83) out of 10, respectively. In multivariable analyses, Caucasian ancestry (adjusted linear regression model estimate [ß] 0.50; 95% confidence interval [CI] 0.17, 0.82), employment (ß 0.76; 95% CI: 0.38, 1.13), diagnosed mental health disorder (ß 0.44; 95% CI: 0.11, 0.78) and previous HCV treatment (ß 0.94; 95% CI: 0.46, 1.43) were independently associated with higher knowledge. Downtown Eastside (DTES) residence (i.e., epicenter of Vancouver's drug scene) was independently associated with lower knowledge (ß -0.48; 95% CI: -0.81, -0.15). Greater HCV knowledge (ß 0.12; 95% CI: 0.07, 0.17) was independently associated with higher HCV treatment willingness. DTES residence (ß -0.31; 95% CI: -0.56, -0.06) and daily crack cocaine smoking (ß -0.52; 95% CI: -0.92, -0.13) were independently associated with lower treatment willingness. CONCLUSION: Socioeconomic factors, such as neighborhood residence and employment, were associated with HCV knowledge. Higher HCV knowledge was associated with more HCV treatment willingness. Our findings suggest that increasing HCV knowledge amongst PWID may be an integral component of the HCV cascade of care and that efforts might be best targeted to individuals with greater socioeconomic disadvantage.

Factors associated with optimal pharmacy refill adherence for antiretroviral medications and plasma HIV RNA non-detectability among HIV-positive crack cocaine users: a prospective cohort study.

BACKGROUND: Crack cocaine use is known to contribute to poor adherence to antiretroviral medications; however, little is known about facilitators of or barriers to effective HIV treatment use among HIV-infected crack cocaine users. We sought to identify correlates of optimal pharmacy refill adherence for antiretroviral medications and plasma HIV RNA viral load (pVL) suppression among this population. METHODS: Data from a prospective cohort of HIV-positive people who use illicit drugs in Vancouver, Canada, were linked to comprehensive HIV clinical monitoring and pharmacy dispensation records. We used multivariable generalized linear mixed-effects modelling to longitudinally identify factors associated with ≥95 % adherence to pharmacy refills for antiretroviral medications and pVL <50 copies/mL among crack cocaine users exposed to highly-active antiretroviral therapy (HAART). RESULTS: Among 438 HAART-exposed crack cocaine users between 2005 and 2013, 240 (54.8 %) had ≥95 % pharmacy refill adherence in the previous 6 months at baseline. In multivariable analyses, homelessness (adjusted odds ratio [AOR]: 0.58), ≥daily crack cocaine smoking (AOR: 0.64), and ≥ daily heroin use (AOR: 0.43) were independently associated with optimal pharmacy refill adherence (all p < 0.05). The results for pVL non-detectability were consistent with those of medication adherence, except that longer history of HAART (AOR: 1.06), receiving a single tablet-per-day regimen (AOR: 3.02) and participation in opioid substitution therapies was independently associated with pVL non-detectability (AOR: 1.55) (all p < 0.05). CONCLUSIONS: Homelessness, and daily crack cocaine and/or heroin use were independently and negatively associated with optimal HAART-related outcomes. With the exception of opioid substitution therapies, no addiction treatment modalities assessed appeared to facilitate medication adherence or viral suppression. Evidence-based treatment options for crack cocaine use that also confer benefits to HAART need to be developed.

Declining trends in exposures to harmful policing among people who inject drugs in Vancouver, Canada.

INTRODUCTION: In 2006, the Vancouver Police Department (VPD) developed an organization-wide drug policy approach, which included endorsing harm reduction strategies for people who inject drugs (PWID). We sought to examine rates of potentially harmful policing exposures and associated HIV risk behaviour among PWID in Vancouver, Canada before and after the VPD policy change. METHODS: Data were derived from two prospective cohort studies of PWID. Multivariable generalized estimating equation models were used to examine changes in the risk of confiscation of drug use paraphernalia and physical violence by the police, as well as changes in the relationship between exposures to the two policing practices and sharing of drug use paraphernalia, before and after the policy change. RESULTS: Among 2193 participants, including 757 (34.5%) women, the rates of experiencing police confiscation of drug use paraphernalia declined from 22.3% in 2002 to 2.8% in 2014, and the rates of reporting experiencing physical violence by the police also declined from 14.1% in 2004 to 2.9% in 2014. In multivariable analyses, the post-policy change period remained independently and negatively associated with reports of confiscation of drug use paraphernalia (adjusted odds ratio (AOR): 0.25; 95% confidence interval (CI): 0.21 to 0.31) and reported physical violence by the police (AOR: 0.76; 95% CI: 0.63 to 0.91). However, experiencing both confiscation of drug use paraphernalia and physical violence by the police (AOR: 1.92; 95% CI: 1.10 to 3.33) and experiencing only confiscation of drug use paraphernalia (AOR: 1.71; 95% CI: 1.34 to 2.19) remained independently and positively associated with sharing of drug use paraphernalia during the post-policy change period. CONCLUSIONS: In our study, two policing practices known to increase HIV risk among PWID have declined significantly since the local police launched an evidence-based drug policy approach. However, these practices remained independently associated with elevated HIV risk after the post-policy change. Although there remains a continued need to ensure that policing activities do not undermine public health efforts, these findings demonstrate that a major shift towards a public health approach to policing is possible for a municipal police force.

Reducing rates of preventable HIV/AIDS-associated mortality among people living with HIV who inject drugs.

PURPOSE OF REVIEW: The modern antiretroviral therapy (ART) era has seen substantial reductions in mortality among people living with HIV. However, HIV-positive people who inject drugs (PWIDs) continue to experience high rates of suboptimal HIV-related outcomes. We review recent findings regarding factors contributing to premature and preventable mortality among HIV-positive PWID, and describe the promise of interventions to improve survival in this group. RECENT FINDINGS: The current leading causes of death among HIV-positive PWID are HIV/AIDS-related causes, overdose, and liver-related causes, including infection with hepatitis C virus. Elevated mortality levels in this population are driven by social-structural barriers to ART access and adherence, particularly criminalization and stigmatization of drug use. In contexts where opioid substitution therapy and ART adherence support programs are widely accessible, evidence highlights comparable levels of survival among HIV-positive PWID and people living with HIV who do not inject drugs. SUMMARY: The life-saving benefits of ART can be realized among HIV-positive PWID when it is paired with strategies that address barriers to evidence-based medical care. Joint administration of ART and opioid substitution therapy, as well as repeal of punitive laws that criminalize drug users, are urgently needed to reduce HIV and injection-related mortality among PWID.

The Impact of Enrolment in Methadone Maintenance Therapy on Initiation of Heavy Drinking among People Who Use Heroin.

BACKGROUND: There is equivocal evidence regarding whether people who use heroin substitute heroin for alcohol upon entry to methadone maintenance therapy (MMT). We aimed to examine the impact of MMT enrolment on the onset of heavy drinking among people who use heroin. METHODS: We derived data from prospective, community-based cohorts of people who inject drugs in Vancouver, Canada, between December 1, 2005, and May 31, 2014. Multivariable extended Cox regression analysis examined the effect of MMT enrolment on the onset of heavy drinking among people who used heroin at baseline. RESULTS: In total, 357 people who use heroin were included in this study. Of these, 208 (58%) enrolled in MMT at some point during follow-up, and 115 (32%) reported initiating heavy drinking during follow-up for an incidence density of 7.8 events (95% CI 6.4-9.5) per 100 person-years. The incidence density of heavy drinking was significantly lower among those enrolled in MMT at some point during follow-up compared to those who did not (4.6 vs. 16.2; p < 0.001). MMT enrolment was not significantly associated with time to initiate heavy drinking (adjusted relative hazard (ARH) 1.27; 95% CI 0.78-2.07) after adjustment for relevant demographic and substance-use characteristics. Age and cannabis use were the only variables that were independently associated with the time to onset of heavy drinking (ARH 0.74; 95% CI 0.58-0.94 and ARH 2.06; 95% CI 1.32-3.19, respectively). CONCLUSION: In this study, MMT enrolment did not predict heavy drinking and may even appear to decrease the initiation of heavy drinking. Our findings suggest younger age and cannabis use may predict heavy drinking. These findings could help inform on-going discussions about the effects of opioid agonist therapy on alcohol consumption among people who use heroin.

Sex-Based Differences in Rates, Causes, and Predictors of Death Among Injection Drug Users in Vancouver, Canada.

In the present study, we sought to identify rates, causes, and predictors of death among male and female injection drug users (IDUs) in Vancouver, British Columbia, Canada, during a period of expanded public health interventions. Data from prospective cohorts of IDUs in Vancouver were linked to the provincial database of vital statistics to ascertain rates and causes of death between 1996 and 2011. Mortality rates were analyzed using Poisson regression and indirect standardization. Predictors of mortality were identified using multivariable Cox regression models stratified by sex. Among the 2,317 participants, 794 (34.3%) of whom were women, there were 483 deaths during follow-up, with a rate of 32.1 (95% confidence interval (CI): 29.3, 35.0) deaths per 1,000 person-years. Standardized mortality ratios were 7.28 (95% CI: 6.50, 8.14) for men and 15.56 (95% CI: 13.31, 18.07) for women. During the study period, mortality rates related to infection with human immunodeficiency virus (HIV) declined among men but remained stable among women. In multivariable analyses, HIV seropositivity was independently associated with mortality in both sexes (all P < 0.05). The excess mortality burden among IDUs in our cohorts was primarily attributable to HIV infection; compared with men, women remained at higher risk of HIV-related mortality, indicating a need for sex-specific interventions to reduce mortality among female IDUs in this setting.

Factors associated with willingness to participate in a pharmacologic addiction treatment clinical trial among people who use drugs.

BACKGROUND AND OBJECTIVES: Although new medications are needed to address the harms of drug addiction, rates of willingness to participate in addiction treatment trials among people who use drugs (PWUD), have not been well characterized. METHODS: One thousand twenty PWUD enrolled in two community-recruited cohorts in Vancouver, Canada, were asked whether they would be willing to participate in a pharmacologic addiction treatment trial. Logistic regression was used to identify factors independently associated with a willingness to participate. RESULTS: Among the 1,020 PWUD surveyed between June 1, 2013 and November 30, 2013, 58.3% indicated a willingness to participate. In multivariate analysis, factors independently associated with a willingness to participate in a pharmacologic addiction treatment trial included: daily heroin injection (Adjusted Odds Ratio [AOR] = 1.75; 95% Confidence Interval [CI]: 1.13 - 2.72); daily crack smoking (AOR = 1.81; 95% CI: 1.23 - 2.66); sex work involvement (AOR = 2.22; 95% CI: 1.21 - 4.06); HIV seropositivity (AOR = 1.49; 95% CI: 1.15 - 1.94); and methadone maintenance therapy participation (AOR = 1.77; 95% CI: 1.37-2.30). DISCUSSION AND CONCLUSIONS: High rates of willingness to participate in a pharmacologic addiction treatment trial were observed in this setting. Importantly, high-risk drug and sexual activities were positively associated with a willingness to participate, which may suggest a desire for new treatment interventions among PWUD engaged in high-risk behavior. SCIENTIFIC SIGNIFICANCE: These results highlight the viability of studies seeking to enroll representative samples of PWUD engaged in high-risk drug use.

The impact of drug use patterns on mortality among polysubstance users in a Canadian setting: a prospective cohort study.

BACKGROUND: Illicit drug use is a well-established risk factor for morbidity and mortality. However, few studies have examined the impact of different drug use patterns on mortality among polysubstance using populations. This study aimed to identify drug-specific patterns of mortality among a cohort of polysubstance using persons who inject drugs (PWIDs). METHODS: PWIDs in Vancouver, Canada were prospectively followed between May 1996 and December 2011. Participants were linked to the provincial vital statistics database to ascertain mortality rates and causes of death. We used multivariate Cox proportional hazards regression to investigate the relationships between drug use patterns (daily alcohol use, heroin injection and non-injection use, cocaine injection, amphetamine injection and non-injection use, crack smoking and speedball injecting) and time to all-cause mortality. RESULTS: 2330 individuals were followed for a median of 61 months (inter-quartile range: 33 - 112). In total, 466 (19.1%) individuals died for an incidence density of 3.1 (95% confidence interval [CI]: 2.8 - 3.4) deaths per 100 person-years. In multivariate analyses, after adjusting for HIV infection and other potential confounders, only daily cocaine injection remained independently associated with all-cause mortality (adjusted hazard ratio [AHR] = 1.36, 95% CI: 1.06 - 1.76). CONCLUSIONS: Although heroin injecting is traditionally viewed as carrying the highest risk of mortality, in this setting, only daily cocaine injecting was associated with all-cause mortality. These findings highlight the urgent need to identify novel treatments and harm reduction strategies for cocaine injectors.